Braided products and apparatus for production of such products are well-knows. Typical of the braiding mechanisms used for such products are disclosed in U.S. Pat. Nos. 776,842 to Horwood, 1,154,964 to Bentley, 1,285,451 to Stanton, 1,358,173 to Penso et al., 1,486,527 to Larkin, 1,785,683 to Mallory, 2,079,836 to Brown et al., 2,200,323 to Barrans et al., 2,452,136 to Marti, 4,158,984 to Griffiths, 4,304,169 to Cimprich et al., 4,333,380 to Kozlowski, 4,716,807 to Fischer, 4,753,149 to Celani, 4,909,127 to Skelton et al. and 4,922,798 to Ivsan. British Patent Publication No. 138,069 dated Sep. 2, 1920 relates to improvements in such braiding devices.
Sutures intended for the repair of body tissues must meet certain requirements: they must be substantially non-toxic, capable of being readily sterilized, they must have good tensile strength and have acceptable knot-tying and knot-holding characteristics and if the sutures are of the bio-absorbable variety, the bio-absorption of the suture must be closely controlled.
Sutures have been constructed from a wide variety of materials including surgical gut, silk, cotton, polyolefins such as polypropylene, polyamides, polyesters such as polyethylene terephthalate, polyglycolic acid, glycolide-lactide copolymer, etc. Although the optimum structure of a suture is that of a monofilament, since certain materials of construction would provide a stiff monofilament suture lacking acceptable handling, knot-tying and knot-holding properties, sutures manufactured from such materials have been provided as braided structures. Thus, for example, sutures manufactured from silk, polyamide, polyester and bio-absorbable glycolide-lactide copolymer are usually provided as multifilament braids.
currently available braided suture products are braided on conventional braider apparatus having yarn bobbin carriers which travel around the perimeter of a braider deck to result in a tubular type braid with the yarns crossing over each other on the surface of the braid. In larger suture sizes, e.g., 5/0 and larger, the tubular braid, or sheath, is constructed about a core structure which is fed through the center of the braider. Known tubular braided sutures, including those possessing cores, are disclosed, e.g., in U.S. Pat. Nos. 3,187,752; 3,565,077; 4,014,973; 4,043,344; and 4,047,533.
Recent attempts to improve the flexibility, hand and tissue drag characteristics of braided sutures have resulted in new braid structures possessing a significantly greater number of sheath yarns for a given overall denier, the sheath yarns being fabricated from individual filaments of finer denier than filaments which are typical of known types of braided sutures. Braided sutures of this type are disclosed and claimed in U.S. patent application Ser. No. 491,215 filed Mar. 9, 1990 now U.S. Pat. No. 5,019,093 on May 28, 1991, and related applications. The foregoing application discloses sutures braided from yarns having a denier in the range of about 0.2 to 6.0 and, optionally, a core having a denier of from about 50 to about 2500 denier. Improvements in such apparatus and methods for continuously braiding fine denier yarns into fine braided products having predetermined construction and appearance suitable for use in body tissue repair are disclosed in parent application Ser. No. 07/569,079, now abandoned in favor of FWC application Ser. No. 08/702,344, incorporated herein by reference, and include a quick release braider bobbin top holder. The foregoing improvements and those of the present application may find application in the manufacture of both tubular braided structures and so-called spiroid braided structures, with or without a core.
SUMMARY OF THE INVENTION
The present invention relates to an improved apparatus for braiding elongate flexible members to form a final braided product, preferably a surgical suture made from fine denier yarns. The braided product may be of the type formed only of a tubular braided sheath, a substantially solid spiroid braid, or a tubular or spiroid braided sheath formed about a center core. In particular, the present invention is directed to improvements which make it possible to quickly mount and/or remove a yarn bobbin onto or from a yarn bobbin carrier with high efficiency and speed and to secure the bobbin to the carrier with a securing mechanism which is simple to operate, does not require a high level of dexterity, and which is not tiring or injurious to the muscles of the operator.
In the braider apparatus of the present invention a plurality of yarn bobbin carriers move about a main carrier support plate to dispense yarns toward a braiding zone where the yarns are braided together to form a final braided product, preferably a surgical suture. The preferred apparatus includes means for controlling tension on the yarns dispensed from the bobbins to form the braided suture product and to control the tension on the final braided product. Each yarn carrier includes a spindle onto which a novel molded bobbin having a central aperture is mounted for rotational movement relative to the spindle. Each bobbin has a number of radial segments engageable with a pawl on the carrier for selectively permitting rotation of the bobbin in response to yarn tension in order to control the dispensing of yarn from the bobbin.
In accordance with the invention, a bobbin top holder base is fixedly mounted relative to the yarn carrier adjacent the top of the yarn carrier spindle and, hence, adjacent to the top of a bobbin situated thereon. The bobbin top holder base has hinge pins, and a bobbin top holder is hingedly mounted to the bobbin holder base at the hinge pins. The bobbin top holder has two longitudinally extending legs defining a slot therebetween and, more specifically, a spindle engaging recess having an inwardly projecting radiused section to engage a corresponding circumferential recess in the spindle adjacent the spindle tip. The bobbin holder legs are formed of a resilient plastic material which is sufficiently flexible to permit the legs to spread apart as the legs are forced over the spindle tip, and resiliently reassume a rest position disposed within the circumferential recess of the spindle to hold the bobbin on the spindle.
In use, the bobbin top holder first is disposed in an unlocked or open position rotated away from the spindle to permit mounting of a bobbin loaded with yarn onto the carrier. After the bobbin is mounted, the bobbin top holder is rotated into contact with the spindle tip with sufficient force to cause the bobbin top holder legs to spread apart and mount over the spindle, resiliently resuming a rest or contracted position disposed within the circumferential recess of the spindle tip, thereby securing the bobbin on the carrier. The braider apparatus thereafter is operated to form a final braided product, preferably a surgical suture. In order to remove an empty bobbin, sufficient upward force is exerted on the bobbin holder legs to cause the bobbin legs to spread apart, leave the spindle recess, and become disengaged from the spindle. The preferred bobbin holder is injection molded of an elastomeric plastic material which is sufficiently resilient to permit many cycles of bobbin mounting without failure of the bobbin top holder.
The bobbin holder of the invention is convenient to use and advantageously improves the efficiency of the preferred braider apparatus.